In testimony before the House Armed Services Committee, Mr. Panetta said the violence in Syria has been “brutal and devastating,” putting the Syrian people “in a desperate” situation.

Iran is helping to prop up Syrian strongmen, Panetta contended, supporting the regime of Syrian President Bashar al-Assad “with material, financial, and technical assistance.” That’s because “no other country stands to lose more than Iran from the eventual fall of the Assad regime,” he added.

For now, the US is in the process of sending “nonlethal” aid, including communications and medical equipment, to the civilian-led opposition in Syria. The Pentagon is also providing humanitarian relief to the tune of $25 million.

These measures are putting pressure on the Assad regime, Panetta argued. He acknowledged, however, that more may need to be done.

“There are legitimate questions” about what steps are needed to bring an end to the Assad regime, he said, “with some arguing for an approach similar to the one we took in Libya.”

Indeed, he said, the US intervention in Libya is “helping to inform the approach of the United States to Syria."

That must include international consensus, clear regional support from the Arab world, and “a clear legal basis” for any US military action, Panetta said.

Should these be found, the Pentagon will “offer substantial US contributions where we can bring unique resources to bear.”

For the time being, “strong sanctions” are “putting Assad under greater pressure than ever before,” Panetta told lawmakers. Any US actions going forward “must keep all options on the table, while recognizing the limitations of military force."

That said, Assad has to go, Panetta warned. “Make no mistake – one way or another, this regime ultimately will meet its end.”